It is well known to form a color image by reacting an oxidized aromatic primary amine color developing agent and a coupler with an exposed silver halide as an oxidizing agent to give an indophenol, indoaniline, indamine, azomethine, phenoxazine, phenazine or the like dye. In such a photographic system, subtractive color photography is used, and color images are formed of yellow, magenta and cyan dyes.
For producing cyan color images, phenol or naphthol couplers are generally used. However, since these couplers have an unfavorable absorption in the green range, they have a serious problem in that they noticeably lower color reproducibility. Therefore, there is a need to overcome this problem.
As a means for overcoming the problem, the heterocyclic compounds described in U.S. Pat. Nos. 4,728,598 and 4,873,185 and European Patent 249,453A2 have been proposed. However, these have severe problems in that the coupling activity thereof is low and the dyes formed therefrom have poor fastness to heat and light. As couplers free from these problems, the pyrrolopyrazoles described in European Patent Laid-Open No. 0456226 have been proposed. These couplers are excellent with respect to coupling activity, color hue and fastness of the dyes formed therefrom, and therefore they may be fairly improved heterocyclic cyan couplers. However, they still are insufficient for practical use. In particular, they have problems in that the dyes formed therefrom often associate with each other in oil droplets to give unnecessary absorption peaks and the cyan fog in the non-exposed area immediately after development is great.